Pre-Scanning Printer with Paper Fingerprinting

ABSTRACT

Techniques for scanning and generating fingerprints for articles prior to the use of the articles. The fingerprinting of the articles is performed such that it is decoupled from the process of using the articles. As a result, the fingerprinting process does not act as a bottleneck to the use of the articles. In one embodiment, a printer is provided that is configured to generate fingerprints for paper sheets loaded into the printer prior to the paper sheets being available for printing. The pre-fingerprinted sheets are then made available for printing. In this manner, the process of fingerprinting of the paper sheets is decoupled from the printing operations performed by the printer. As a result, the fingerprinting process does not act as a bottleneck to the printing process.

CROSS-REFERENCES TO RELATED APPLICATIONS

The present application herein incorporates by reference for allpurposes the entire contents of the following:

(1) PCT Publication No. WO 2005/088533, entitled “AuthenticityVerification Methods, Products, and Apparatuses” filed Mar. 9, 2005 andpublished Sep. 22, 2005;

(2) UK Patent Application GB 2417707A; and

(3) U.S. application Ser. No. 11/495,613 (Atty. Docket No.:015358-010910US) filed Jul. 28, 2006.

BACKGROUND OF THE INVENTION

The present invention relates to fingerprinting of articles, and moreparticularly to techniques for fingerprinting an article prior to use ofthe article such that the use of the article is not impacted by thefingerprinting process.

Techniques have been developed for generating fingerprints for articlesbased upon the physical structure of the article. In one such technique,developed by Ingenia Technology Limited (ITL) located in London, UnitedKingdom (www.ingeniatechnology.com), a scanner is configured to scan oneor more areas of an article using a light beam (e.g., a laser beam) anddetect the scatter pattern of the light reflected from the scanned areaof the article. The scatter pattern data is then used to generate afingerprint or digital signature for the scanned article. Due todifferences in the surface structure of the articles at the microscopiclevel, the light scatter pattern is generally different for differentarticles. As a result, the fingerprint generated for an article ishighly distinctive of that article and can be used to identify orauthenticate that article. ITL has developed scanners that are capableof generating fingerprints for articles such as paper sheets. Adescription of their technology is provided in PCT Publication No. WO2005/088533, entitled “Authenticity Verification Methods, Products, andApparatuses” filed Mar. 9, 2005 and published Sep. 22, 2005.

UK Patent Application GB 2417707A assigned to ITL describes techniquesfor using a scanner to obtain fingerprints or digital signatures for asheet of paper as the paper is being printed. The digital signatureobtained for a paper sheet is stored in a database with an image of whatwas printed on the paper sheet. Subsequently, the stored information isused to determine the authenticity of the paper sheet.

The fingerprint scans described above however tend to be slow due to thevast amount of data collection and processing involved in generating thefingerprints. The print speeds in a normal printer are usually howevermuch higher than current technology allows for generating thefingerprints. For example, normal printers commonly run at a page every2 seconds—this is roughly double the scan speed of conventional paperfingerprinting devices. Hence, applications which envisionfingerprinting pages as part of the printing process, as described inPCT Publication No. WO 2005/088533 and UK Patent Application GB2417707A, are likely to be very slow due to the bottleneck offingerprint scanning and processing that occurs as part of the printing.

BRIEF SUMMARY OF THE INVENTION

Embodiments of the present invention provide techniques for scanning andgenerating fingerprints for articles prior to the use of the articles.The fingerprinting of the articles is performed such that it isdecoupled from the process of using the articles. As a result, thefingerprinting process does not act as a bottleneck to the use of thearticles. In one embodiment, a printer is provided that is configured togenerate fingerprints for paper sheets loaded into the printer prior tothe paper sheets being available for printing. The pre-fingerprintedsheets are then made available for printing. In this manner, the processof fingerprinting of the paper sheets is decoupled from the printingoperations performed by the printer. As a result, the fingerprintingprocess does not act as a bottleneck to the printing process.

According to an embodiment of the present invention, techniques areprovided for fingerprinting paper sheets in a device such as a printer.A fingerprint is generated for a paper sheet from a first tray in theprinter. Information is stored in memory associating the fingerprintwith the paper sheet. The paper sheet is then transported back to thefirst tray, wherein the paper sheet is made available for printing. Inone embodiment, the process of generating a fingerprint may be performedupon detecting insertion of the first tray in the printer. The systemresponsible for fingerprinting may comprise a scanner that receives thepaper sheet to be fingerprinted from the first tray.

A request may be received to print an electronic document. In oneembodiment, in response, at least one fingerprinted paper sheet isselected from the first tray for printing the electronic document, and aprinted document is generated using the at least one fingerprinted papersheet from the first tray. Information may be stored for the at leastone fingerprinted paper sheet associating the fingerprint generated forthe at least one fingerprinted paper sheet with information related tothe electronic document. The information related to the electronicdocument may comprise information such as information related tocontents of the electronic document printed on the at least onefingerprinted paper sheet.

In one embodiment, a non-fingerprinted paper sheet may be selected froma second tray in the printer different from the first tray and theprinted document may be generated using the non-fingerprinted papersheet. The request to print may also specify a page of the electronicdocument for which a fingerprinted paper sheet is to be used forprinting the electronic document.

According to an embodiment of the present invention, paper sheets may bemarked so as to avoid re-fingerprinting of a previously fingerprintedpaper sheet. In this embodiment, prior to fingerprinting a paper sheet,it is determined if the paper sheet received from the first tray forfingerprinting comprises a mark indicating that the paper sheet has beenpreviously fingerprinted. A fingerprint is generated for the paper sheetonly if it is determined that the paper sheet does not comprise the markor the paper sheet comprises a mark that is not decipherable by theprinter. After a paper sheet has been fingerprinted, it is marked toindicate that the paper sheet has been fingerprinted.

Different techniques may be used to mark a paper sheet. In oneembodiment, the paper sheet may be marked by printing a code on thepaper sheet. The code may be for example a barcode, a code printed usinginfrared ink, or a code printed using an ink that becomes transparentupon exposure to light. Steganographic techniques may also be used tomark a paper sheet.

According to an embodiment of the present invention, techniques areprovided for fingerprinting a paper sheet in a printer. A set of one ormore paper sheets may be selected from a stack of paper sheets stored ina first tray of the printer. A fingerprint may then be generated foreach paper sheet in the selected set of paper sheets. Information may bestored in memory, for each paper sheet in the set of paper sheets,associating the fingerprint generated for the paper sheet with the papersheet. After fingerprinting, the set of paper sheets may be transportedto a second tray in the printer separate from the first tray. In oneembodiment, a request may be received to print an electronic document.In response, a printed document may be generated wherein the printeddocument comprises a fingerprinted paper sheet from the second tray anda non-fingerprinted paper sheet from the first tray.

According to an embodiment of the present invention, techniques areprovided for preparing an article for use by a device configured toperform a function using the article. The article is fingerprinted andonly then is it made available for use by the device for performing thefunction.

The foregoing, together with other features, embodiments, and advantagesof the present invention, will become more apparent when referring tothe following specification, claims, and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified block diagram of a printer that incorporates anembodiment of the present invention;

FIG. 2 is a schematic view of an illustrative embodiment of a scannerdepicted in FIG. 1 in accordance with an embodiment of the presentinvention;

FIG. 3 is a simplified high-level flowchart depicting a fingerprintingprocess performed by a printer according to an embodiment of the presentinvention;

FIG. 4 is a simplified high-level flowchart depicting a fingerprintingprocess performed by a printer in which fingerprinted paper sheet aremarked according to an embodiment of the present invention;

FIG. 5 is a simplified block diagram of a printer that incorporatesmultiple paper trays according to an embodiment of the presentinvention;

FIG. 6 is a simplified high-level flowchart depicting a method ofgenerating a printed document by interleaving fingerprinted paper sheetswith non-fingerprinted paper sheets according to an embodiment of thepresent invention;

FIG. 7 is a simplified block diagram of a printer wherein paper sheetsare selected for fingerprinting from one tray and returned to anothertray according to an embodiment of the present invention; and

FIG. 8 is a simplified high-level flowchart depicting a fingerprintingprocess performed by a printer according to an embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

In the following description, for the purposes of explanation, specificdetails are set forth in order to provide a thorough understanding ofthe invention. However, it will be apparent that the invention may bepracticed without these specific details.

Embodiments of the present invention are configured to scan and generatefingerprints for articles prior to the use of the articles. Thefingerprinting of the articles is performed such that it is decoupledfrom the process of using the articles. As a result, the fingerprintingprocess does not act as a bottleneck to the use of the articles.

According to an embodiment of the present invention, a printer isprovided that is configured to generate fingerprints for paper sheetsloaded into the printer prior to the paper sheets being available forprinting. The pre-fingerprinted sheets are then made available forprinting. In this manner, the process of fingerprinting of the papersheets is decoupled from the printing operations performed by theprinter. As a result, the fingerprinting process does not act as abottleneck to the printing process.

FIG. 1 is a simplified block diagram of a printer 100 that incorporatesan embodiment of the present invention. Printer 100 depicted in FIG. 1is merely illustrative of an embodiment incorporating the presentinvention and is not intended to limit the scope of the invention asrecited in the claims. Embodiments of the present invention may beincorporated into various other systems and devices. One of ordinaryskill in the art would recognize other variations, modifications, andalternatives. Printer 100 may be embodied in various differentconfigurations, as a standalone printer, as a networked printer, as partof a multifunction printer or device, in a facsimile machine, and thelike.

As depicted in FIG. 1, printer 100 comprises a paper bin/tray 102, amemory 104 associated with the tray, a fingerprinting system 106, aprint engine 108, and a print driver 110. Paper bin/tray 102 provides anarea for storing paper sheets that are to be used for printing. A usermay load paper into printer 100 by putting the paper sheets in tray 102and then inserting paper tray 102 into printer 100 or by closing papertray 102. For purposes of this application, inserting a paper tray inprinter 100 is intended to also include closing tray/bin 102 of printer100.

Fingerprinting system 106 is configured to scan one or more paper sheetsfrom tray 102 and generate fingerprints for the scanned sheets. In oneembodiment, fingerprinting system 106 is configured to detect when apaper tray 102 has been inserted into printer 100. Upon detecting aninsertion or closure of paper tray 102, fingerprinting system 106 isconfigured to scan and generate fingerprints for the paper sheets storedin tray 102 prior to the paper sheets being available for printing. Aspart of the fingerprinting process, a paper sheet is transported fromtray 102 to fingerprinting system 106, fingerprinting system 106generates a fingerprint for the paper sheet, and then the fingerprintedsheet is transported back to tray 102. Accordingly, a paper sheetselected for fingerprinting from tray 102 is returned back to tray 102after the fingerprinting process (as depicted by paper path 112 depictedin FIG. 1). In one embodiment, the paper sheets may be returned to tray102 in the same order as they were originally positioned in tray 102. Inother embodiments, the papers may be replaced in the tray in reverseorder, or in any other order, so long as that order is known andpredictable and can be used to make a one-to-one mapping between scannedfingerprints and the position of the paper in the tray.

In one embodiment, all the paper sheets in the stack of paper sheets intray 102 are fingerprinted. This avoids problems with the paper sheetsbeing removed or reordered within the paper stack in tray 102 since aprevious fingerprinting operation. In alternative embodiments, asdescribed below in further detail, a subset of the paper sheets in thepaper stack stored in tray 102 may be fingerprinted.

In the embodiment depicted in FIG. 1, fingerprinting system 106comprises a scanner 114 and a processor 116. Scanner 114 is configuredto scan one or more areas of a paper sheet and collect data pointsrepresentative of the light scattered by the scanned areas. Processor116 is configured to control the operations of scanner 114 and generatea fingerprint for a paper sheet based upon the data points collected byscanner 114 from scanning the paper sheet.

Scanner 114 is configured to scan and collect data points for an articlesuch as a paper sheet. The data points are then used to generate afingerprint (or signature) for the paper sheet. In one embodiment,scanner 114 is capable of directing a coherent light beam (e.g., a laserbeam) onto an area of the surface of a paper sheet. The area of thepaper sheet that is impinged by the light beam is referred to as thescanned area of the paper sheet. Scanner 114 is configured to detectsignal components scattered from the scanned area of the paper sheet.During a scan, scanner 114 is configured to detect and record a largenumber of details of the way the light beam is reflected off the surfaceof the scanned paper sheet. Scanner 114 may comprise a set of one ormore detectors that are configured to detect the scattered light signalsand collect data points corresponding to the scattering.

The detectors in scanner 114 are sufficiently sensitive to detectscattered light due to surface irregularities of the paper sheet of lessthan a few hundred nanometers in size. Due to differences in surfaces ofarticles at the microscopic level, a unique scatter response is receivedfrom each article. Microscopic irregularities on the surface of thearticle cause the light beam to be scattered differently for differentarticles. Accordingly, for a paper sheet, due to the structure of thepaper fibers of the paper sheet, the paper sheet surface provides acomplex scattering response of the laser beam that is unique andcharacteristic of the paper sheet. The scatter response for one papersheet is different from the scatter response from another paper sheetsince, at the microscopic level, the structures of the surfaces aredifferent. The scattered response for a paper sheet may thus be used asa basis for generating a fingerprint (or signature) for the paper sheetthat is unique to the paper sheet.

FIG. 2 is a schematic view of an illustrative embodiment of a scanner114 depicted in FIG. 1 in accordance with an embodiment of the presentinvention. The components of scanner 114 may be enclosed in a housing orassembly 202. In the embodiment depicted in FIG. 2, the principaloptical components of scanner 114 include a laser source 204 forgenerating a coherent laser beam 206 for scanning an area of a surfaceof an article such as a paper sheet. Laser beam 206 is focused by a lens210 to form a focused beam that passes through a reading volume 212.

Scanner 114 comprises a detector arrangement comprising a plurality ofphotodetector elements 208 a-208 d. Although the specific embodimentillustrated in FIG. 2 shows four photodetector elements, it will beappreciated that other numbers of photodetector elements may beemployed. Photodetectors 208 a-208 d are distributed about the laserbeam at different angles to detect light scattered from the scanned areaof the article present in the reading volume 212.

A drive motor 214 is arranged in housing 202 for providing motion of theoptics components via suitable bearings 216 or other means. Drive motor214 serves to move the coherent beam and this controls the area of thearticle that is scanned. Drive motor 214 also controls the speed or rateof the scan. The intensity of light beam 206, speed of drive motor 214,and the position of photodetectors 208 a-208 d may be user-controllable.

Some of the basic operations of a scanner such as scanner 114 depictedin FIGS. 1 and 2 (and other figures) are also described in PCTPublication No. WO 2005/088533, the entire contents of which are hereinincorporated by reference for all purposes.

In one embodiment, fingerprinting system 106 may be implemented in papertray 102. Paper trays often have significant extra space because of theneed to handle large sheets. Fingerprinting system 106 may be containedin this extra space. In other embodiments, fingerprinting system 106 maybe attached to tray 102. Memory 104 may also be part of tray 102.

The scanning and data collection technique used by scanner 114 describedabove is strongly dependent upon the manner in which scanner 114performs the scan. For example, the data points collected from a scanare strongly dependent upon the scanned area of article or paper sheet.Different scanned areas of the same paper sheet may yield different datapoints and thus different fingerprints for the same paper sheet.Accordingly, in one embodiment, the area (or areas) of a paper sheetscanned by scanner 114 is fixed such that the same area is scannedduring subsequent scans. In another embodiment, the parameters(including the scanned area) used for scanning from one scan to anothermay be different, as described in U.S. application Ser. No. 11/495,613(Atty. Docket No.: 015358-010910US) filed Jul. 28, 2006.

Referring back to FIG. 1, data points collected by scanner 114 for anarticle such as a paper sheet are communicated to processor 116 forgeneration of a digital fingerprint for the article or paper sheet.Processor 116 is configured to process the data points received fromscanner 114 and produce a digital fingerprint for the scanned article.

The fingerprint information generated by fingerprinting system 106 for apaper sheet is then stored. In one embodiment, the fingerprintinformation for fingerprinted paper sheets may be stored in a memory 104associated with tray 102 in which the fingerprinted sheets are stored.Information is stored associating the generated fingerprints with theircorresponding paper sheets. In one embodiment, the association is madeby storing information identifying the positions of the paper sheets inthe paper stack in tray 102 and associating each position with afingerprint generated for the paper sheet in that position. The contentsof memory 104 may be reset each time tray 102 is removed to avoid anyproblems caused by possible reordering of the papers in tray 102.

As previously described, in one embodiment, after a paper sheet has beenfingerprinted by fingerprinting system 106, the paper sheet is returnedback to tray 102. The paper sheets may be returned to tray 102 in thesame order as present in tray 102 prior to the fingerprinting. This maybe done, for example, by starting the fingerprinting operation on sheetsfrom the bottom of the stack of sheets, and returning the sheets back tothe tray on the top. As part of this process, once a page is found thathas already been fingerprinted, this indicates that all the paper sheetsin the tray have been fingerprinted and fingerprinting may be stopped. Asmall pin can also be inserted between the fingerprinted sheets and thenon-fingerprinted sheets to separate them. Once all the sheets have beenfingerprinted, the fingerprinted paper sheets are then made availablefor printing. In other embodiments, the papers may be replaced in thetray in reverse order, or in any other order, so long as that order isknown and predictable and can be used to make a one-to-one mappingbetween scanned fingerprints and the position of the paper in the tray.

Print driver 110 provides an interface for receiving requests 118 toprint one or more electronic documents. Examples of an electronicdocument is a document created using a word editor, an image, aphotograph, a web page, a spreadsheet, an email, or any document storedin electronic form. Upon receiving a request to print an electronicdocument, print driver 110 is configured to send a signal to printengine 108 to print the electronic document. In the embodiment depictedin FIG. 1, print driver 110 is part of printer 100. In an alternativeembodiment, print driver 110 may be part of or resident on a processingsystem that is coupled to printer 100 and which is configured toinitiate print requests for printer 100. The processing system may becoupled to printer 100 via wired or wireless communication links.

Print engine or print module 108 is configured to generate a printeddocument 120 by printing the electronic document using one or more papersheets from paper tray 102. As part of the printing process, printengine 108 is configured to select a paper sheet from tray 102 forprinting and then use the sheet for printing. Multiple sheets may beused for printing a multi-page electronic document. The resultantprinted document 120 comprises pages that have been fingerprinted. Thesefingerprints may then be used to authenticate the document 120 (forexample, as described in PCT Publication No. WO 2005/088533 and UKPatent Application GB 2417707A).

In addition to generating a physical printed document 120 using one ormore paper sheets from tray 102, print engine 108 is also configured tostore information related to the sheets used for the printing. In oneembodiment, print engine 108 is configured to update the informationstored in memory 104. As previously described, after the fingerprintingoperation is performed by fingerprinting system 106, informationassociating the fingerprints with their corresponding paper sheets isstored in memory 104. In one embodiment, the association is made bystoring information identifying the positions of the paper sheets in thepaper stack in tray 102 and associating each position with a fingerprintgenerated for the paper sheet in that position. After a fingerprintedpaper sheet has been used for generating printed document 120, the entryfor that sheet may be updated with information related to the electronicdocument which is printed using the sheet. For example, in oneembodiment, the entry for a fingerprinted paper sheet may be updatedwith information identifying the contents printed on that sheet. Inanother embodiment, the entry for a fingerprinted paper sheet in memory104 may be updated with information identifying the electronic documentor page of the electronic document printed on that sheet.

Information related to the printed sheets may be stored in memory 104 orin some other memory location. For example, in the embodiment depictedin FIG. 1, the information may be stored locally in memory 104 ofprinter 100. In alternative embodiments, the information may becommunicated and stored on some other device or system or memorylocation that is remote from printer 100 and may be coupled to printer100 via communication links or via a communication network (e.g., theInternet). Printer 100 may then access this information from the remotelocations.

FIG. 3 is a simplified high-level flowchart 300 depicting afingerprinting process performed by a printer according to an embodimentof the present invention. The processing depicted in FIG. 3 may beperformed by software modules (code, instructions), hardware modules, orcombinations thereof. The processing may be performed by fingerprintingsystem 106. Flowchart 300 depicted in FIG. 3 is merely illustrative ofan embodiment of the present invention and is not intended to limit thescope of the present invention. Other variations, modifications, andalternatives are also within the scope of the present invention.

As depicted in FIG. 3, fingerprinting system 106 detects when a papertray has been inserted in the printer (step 302). Steps 304, 306, 308,and 310 are performed upon detecting insertion of a paper tray in theprinter. A paper sheet is transported from the paper tray to thefingerprinting system for fingerprinting (step 304). The fingerprintingsystem scans the paper sheet received from the paper tray and generatesa fingerprint for the paper sheet (step 306). Information is then storedassociating the fingerprinted paper sheet with the generated fingerprint(step 308). The information may be stored in a memory associated withthe paper tray. In one embodiment, the position of the fingerprintedsheet within the stack of paper sheets in the paper tray is stored andthe generated fingerprint is associated with the position information,thereby associating the fingerprint with the paper sheet. Thefingerprinted paper sheet is then returned back to the paper tray fromwhere it was removed and it made available for printing (step 310). Thefingerprinted paper sheet may then subsequently be used to generate aprinted document in response to a print request/command.

Steps 304, 306, 308, and 310 may be applied to multiple paper sheetsstored in the paper tray. The paper sheets may be returned to tray 102in the same order as they were originally positioned in tray 102. Inother embodiments, the papers may be replaced in the tray in reverseorder, or in any other order, so long as that order is known andpredictable and can be used to make a one-to-one mapping between scannedfingerprints and the position of the paper in the tray. In oneembodiment, all the paper sheets in the paper tray are fingerprinted. Inalternative embodiments, less than all sheets (a subset) in the tray maybe fingerprinted.

As described above, a paper sheet that is to be fingerprinted is notmade available for printing until after the paper sheet has beenfingerprinted. Further, the fingerprinting operation is initiated uponthe paper sheet being loaded into a printer and not in response to aprint command. In this manner, the paper sheets are fingerprintedoffline from the actual printing operation. The fingerprinting operationis thus decoupled from the printing operation. A stack of pre-scannedand pre-fingerprinted paper sheets are thus made available for use bythe printer. When the printer receives a print request, the printer mayselect one or more fingerprinted paper sheets from the stack ofpre-fingerprinted paper sheets for the printing. The fingerprintingoperation does not have to be performed inline with the printingoperation. As a result, the fingerprinting operation does not act as abottleneck for the printing operation since a stack of previouslyfingerprinted sheets is available for printing. The printing operationmay thus be performed at high speeds as desired.

In the embodiment described above, each paper sheet in the stack ofpaper sheets in tray 102 is fingerprinted each time that tray 102 isinserted into printer 100. Since the fingerprinting operation isexpensive in terms of time, it is desirable that the number of timesthis operation is performed be reduced. According to one technique, apaper sheet that has been fingerprinted is marked to indicate that thesheet has been fingerprinted. In such an embodiment, fingerprintingsystem 106 may be configured to mark each paper sheet when that papersheet is fingerprinted. In such an embodiment, as part of thefingerprinting operation fingerprinting system 106 is configured tofirst check if a paper sheet presented for fingerprinting contains amark that can be interpreted by fingerprinting system 106 and thatindicates to fingerprinting system 106 that the sheet has beenpreviously fingerprinted by fingerprinting system 106. If such a mark isfound on the paper sheet then fingerprinting for that paper sheet isskipped since the paper sheet has been previously fingerprinted. In thismanner, only a paper sheet that is unmarked (thereby indicating that thepaper sheet has not been previously fingerprinted) or whose mark is notunderstandable by fingerprinting system 106 (possibly because the papersheet has been marked by another printer and then inserted into yetanother printer that is fingerprinting the paper sheet) isfingerprinted. This produces cost savings in terms of time by avoidingre-fingerprinting of a previously fingerprinted sheet.

FIG. 4 is a simplified high-level flowchart 400 depicting afingerprinting process performed by a printer in which the fingerprintedpaper sheet is marked according to an embodiment of the presentinvention. The processing depicted in FIG. 4 may be performed bysoftware modules (code, instructions), hardware modules, or combinationsthereof The processing may be performed by fingerprinting system 106.Flowchart 400 depicted in FIG. 4 is merely illustrative of an embodimentof the present invention and is not intended to limit the scope of thepresent invention. Other variations, modifications, and alternatives arealso within the scope of the present invention.

As depicted in FIG. 4, processing is initiated when insertion of a papertray is detected (step 402). Step 402 is similar step 302 depicted inFIG. 3. A paper sheet is then transported from the paper tray to thefingerprinting system (step 404). Step 404 is similar to step 304 inFIG. 3. The fingerprinting then determines whether the paper sheetreceived from the paper tray comprises a mark that can be read by thefingerprinting system and indicates to the fingerprinting system thatthe paper sheet has been previously fingerprinted and that thefingerprint is known by the fingerprinting system (step 406). If it isdetermined in 406 that the particular paper sheet has been previouslyfingerprinted, then the paper sheet is returned to the paper traywithout fingerprinting and the paper sheet is made available forprinting (step 416).

Steps 408, 410, 412, and 414 are performed only if it is determined in406 that either the paper sheet contains no mark thereby indicating thatit has not been previously fingerprinted or the paper sheet contains amark that cannot be deciphered by the fingerprinting system. Thispossibly may be due to the paper sheet being fingerprinted by anothermachine or the memory being erased. The fingerprinting system scans thepaper sheet and generates a fingerprint for the paper sheet (step 408).Step 408 is similar to step 306 in FIG. 3. The paper sheet is thenmarked to indicate that is has been fingerprinted (step 410).Information is then stored associating the paper sheet with thegenerated fingerprint (step 412). The information may be stored in amemory associated with the paper tray. Step 412 is similar to step 308in FIG. 3. In one embodiment, the code used to mark a sheet may be usedto identify the paper sheet and may be stored in a database in memory104 and associated with a fingerprint generated for that sheet. The codemay be as a key to find the corresponding fingerprint. The code is usedto locate a fingerprint for a paper sheet. The fingerprinted paper sheetis then returned to the paper tray and made available for printing (step414). Step 414 is similar to step 310 in FIG. 3. Steps 404, 406, 408,410, 412, 414, and 416 may be repeated for all paper sheets in tray 102.

Various different techniques may be used to mark a paper sheet. In oneembodiment, a paper sheet is marked with a machine readable code such asa barcode. For example, for a paper sheet, the code may comprise aunique number, like a serial number which is paired in memory with thepaper's fingerprint information. The code may be printed on differentlocations on the paper sheet such as the bottom of the paper sheet, thetop of the paper sheet, etc. Different techniques may be used to printthe code on a paper sheet. In one embodiment, an ink may be used forprinting the code that becomes transparent when exposed to light for awhile. Infrared inks may also be used. In one embodiment, the code maybe in the form of a barcode that is readable by fingerprinting system106 at a very high speed compared to fingerprinting. In one embodiment,steganographic techniques such as subtle color variations may also beused to mark a paper sheet. In general, if a sheet is marked and themarked code is recognized by the printer and the mapping between thecode and the known fingerprint information is stored in the printer ortray memory, the paper sheet does not have to be fingerprinted again(and it does not matter if someone took the paper sheets out of theprinter tray and shuffled them). The code is thus used to determinewhether or not a paper sheet should be fingerprinted. The purpose of themarks is to avoid re-fingerprinting the page in the presence of humanactions like reordering the paper in the tray, moving the tray to adifferent printer, or any other action which would disturb theassociation between tray and paper position and the scanned fingerprintdata.

In the embodiments described above, the fingerprinted paper sheets arereturned to the same tray in which the paper sheets were stored in priorto the fingerprinting. In alternative embodiments, in printers withmultiple trays, separate trays may be used for storing paper sheets thatare to be fingerprinted and sheets that are not fingerprinted. FIG. 5 isa simplified block diagram of a printer 500 that incorporates multiplepaper trays according to an embodiment of the present invention. Printer500 depicted in FIG. 5 is merely illustrative of an embodimentincorporating the present invention and is not intended to limit thescope of the invention as recited in the claims. Embodiments of thepresent invention may be incorporated into various other systems anddevices. One of ordinary skill in the art would recognize othervariations, modifications, and alternatives.

Printer 500 is similar to printer 100 depicted in FIG. 1 but has twotrays 502 and 504 and a paper selector module 508. Printer 500 isconfigured such that paper stored in tray 502 is fingerprinted whilepaper stored in tray 504 is not fingerprinted. Accordingly, tray 502 isused for storing paper sheets that are to be fingerprinted and forstoring the fingerprinted sheets after the fingerprinting operation hasbeen performed. The sheets loaded into tray 502 are fingerprinted in themanner as described above for tray 102 in FIG. 1. Fingerprinting system106 is configured to detect the insertion of tray 502 and fingerprintthe paper sheets stored in tray 502. The fingerprinted sheets are thenreturned back to tray 502 (as indicated by paper path 506). The papersheets from tray 502 may be fingerprinted according to flowchart 300depicted in FIG. 3 or flowchart 400 depicted in FIG. 4. Information maybe stored in memory 104 associated with tray 502 associating thefingerprinted sheets with their corresponding fingerprints. Theinformation may also be stored in other locations local to printer 500or remote from printer 500.

Tray 504 (and potentially other trays) is used for storing normalun-fingerprinted paper sheets and paper sheets that will not befingerprinted. In this manner, in printer 500, the fingerprinted sheetsand the non-fingerprinted sheets are segregated from each other intoseparate trays.

When printer 500 receives a request 118 to print an electronic document,the electronic document is printed to produce printed document 510 byinterleaving one or more fingerprinted paper sheets from tray 502 andnon-fingerprinted sheets from tray 504. In one embodiment, printer 500is configured to use at least one fingerprinted paper sheet forproducing printed document 510. Interleaving enables a printed document510 to be produced wherein a subset of the pages of the document arefingerprinted paper sheets.

Paper selector module 508 is configured to select the paper sheets,either fingerprinted paper sheets from tray 502 or non-fingerprintedpaper sheets from tray 504, to be used for printing a document such thatfingerprinted sheets are interleaved with the non-fingerprinted sheetsin generating a printed document 510. In one embodiment, when printer500 receives a print request/command 118, a signal is sent to paperselector module 508 to initiate the paper sheet selection process. Paperselector 508 then selects one or more sheets from tray 502 and tray 504for printing the document. The selected paper sheets are then providedin an interleaved manner to print engine 108 for generating printeddocument 510. In one embodiment, paper selector module 508 ensures thatprinted document 510 comprises at least one fingerprinted sheet whichcan then be subsequently used for authenticating the printed document.

Different techniques may be used to interleave fingerprinted papersheets with non-fingerprinted paper sheets while generating a printeddocument. In one embodiment, the fingerprinted sheets may be randomlyselected and interleaved with non-fingerprinted sheets. In anotherembodiment, fingerprinted sheets may be selected at regular intervals(e.g., every two pages) and used for generating the printed document,while non-fingerprinted sheets are used for printing the other pages. Inone embodiment, the print request/command may specify which pages are tobe printed using fingerprinted sheets. For example, the print commandmay indicate that the first and last page of the document is to beprinted on fingerprinted sheets. In this manner, a user who initiatesthe print command may specify the pages for which a fingerprinted sheetis to be used. Only the specified pages are then printed usingfingerprinted paper sheets. Other techniques may also be used forinterleaving fingerprinted sheets with non-fingerprinted sheets.

Interleaving of fingerprinted paper sheets with non-fingerprinted papersheets reduces the number of fingerprinted paper sheets required forprinting documents. Only a subset of paper sheets of a printed documentneed to be fingerprinted sheets, the others can be non-fingerprintedsheets. As a result of the subsetting, the number of paper sheets thatare needed to print a document is reduced. This translates to areduction in the amount of scanning and fingerprinting that needs to beperformed by printer 500. This in turn translates to savings in time andcosts by reducing the number of times the expensive fingerprintingprocess has to be performed.

FIG. 6 is a simplified high-level flowchart 600 depicting a method ofgenerating a printed document by interleaving fingerprinted paper sheetswith non-fingerprinted paper sheets according to an embodiment of thepresent invention. The processing depicted in FIG. 6 may be performed bysoftware modules (code, instructions), hardware modules, or combinationsthereof. The processing may be performed by printer 500. Flowchart 600depicted in FIG. 6 is merely illustrative of an embodiment of thepresent invention and is not intended to limit the scope of the presentinvention. Other variations, modifications, and alternatives are alsowithin the scope of the present invention.

As depicted in FIG. 6, the printing process is initiated upon receivinga request/command to print an electronic document (step 602). The paperselector module then selects one or more paper sheet from a tray storingfingerprinted sheets or from a tray storing non-fingerprinted sheets toperform the printing (step 604). Various techniques may be used forselecting fingerprinted sheets and non-fingerprinted sheets. In oneembodiment, at least one fingerprinted paper sheet may be selected in604. A fingerprinted paper sheet may be selected randomly or at regularintervals. If the print request/code module specifically identifiespages for which a fingerprinted sheet is to be used, then afingerprinted paper sheet is selected for printing those specifiedpages. A printed document is then generated by interleaving thefingerprinted and non-fingerprinted paper sheets selected by the paperselector module in 604 (step 606). Information stored for eachfingerprinted paper sheet that is used for printing is then updated(step 608). As previously described, after the fingerprinting operationis performed, information associating the fingerprints with theircorresponding paper sheets is stored in a memory. This information maybe updated in step 608. After a fingerprinted paper sheet has been usedfor generating the printed document, the entry for that sheet may beupdated with information related to the electronic document which isprinted using the sheet. For example, in one embodiment, the entry for afingerprinted paper sheet may be updated with information identifyingthe contents printed on that sheet. In another embodiment, the entry fora fingerprinted paper sheet in memory 104 may be updated withinformation identifying the electronic document or page of theelectronic document printed on that sheet.

In the embodiments described above, the sheets to be fingerprinted areselected from one tray, sent to the fingerprinting system forfingerprinting, and are then returned to the same tray. In analternative embodiment, the paper sheets may be selected forfingerprinting from a first tray and after fingerprinting may beforwarded and stored in a second tray that is separate from the firsttray. FIG. 7 is a simplified block diagram of a printer 700 whereinpaper sheets are selected for fingerprinting from one tray and returnedto another tray according to an embodiment of the present invention.Printer 700 depicted in FIG. 7 is merely illustrative of an embodimentincorporating the present invention and is not intended to limit thescope of the invention as recited in the claims. Embodiments of thepresent invention may be incorporated into various other systems anddevices. One of ordinary skill in the art would recognize othervariations, modifications, and alternatives.

Printer 700 is quite similar to printer 500 depicted in FIG. 5 with thedifference that paper sheets to be fingerprinted are selected from afirst tray and after fingerprinting are deposited into a second traythat is separate from the first tray. Accordingly, one or more papersheets may be loaded into a first tray 702. One or more paper sheetsfrom first tray 702 are selected to be fingerprinted and sent tofingerprinting system 106. After being fingerprinted, the fingerprintedsheets are deposited in a second tray 704 that is separate from firsttray 702. The paper path 706 for the fingerprinting process is thus fromfirst tray 702 to fingerprinting system 106 to second tray 704. Thefingerprinting process may be initiated by fingerprinting system 106when the number of fingerprinted sheets in second tray 704 falls below apreconfigured threshold. When the supply of fingerprinted paper sheetsfall below the threshold, then paper sheets may be selected from firsttray 702 for fingerprinting to replenish the supply in second tray 704.Information associating the fingerprinted sheets with theircorresponding fingerprints may be stored in memory 104 associated withsecond tray 704. In this manner, in printer 700, the fingerprintedsheets and the non-fingerprinted sheets are segregated from each otherinto separate trays.

In the embodiment depicted in FIG. 7, second tray 704 acts as a cache offingerprinted paper sheets and printer 700 is able to perform printingat high speed using non-fingerprinted paper sheets from first tray 702and fingerprinted paper sheets from second tray 704. In one embodiment,second tray 704 that is used for storing the fingerprinted paper sheetsmay be an internal tray of printer 700 and may not be user accessible.

Not all the paper sheets in first tray 702 need be fingerprinted. Only asubset of the sheets from first tray 702 may be fingerprinted. Thesheets may be selected from first tray 702 and fingerprinted at regularintervals or whenever the supply of fingerprinted paper sheets in secondtray 704 falls below some preconfigured threshold. Accordingly, papersheets from first tray 702 are used to replenish the fingerprinted papersheets in second tray 704.

Upon receiving a print request/command 118, paper selector module 508 isconfigured to select one or more paper sheets from first tray 702 andsecond tray 704 for generating printed document 510. The selected sheetsare interleaved in generating printed document 510. In one embodiment,when printer 700 receives a print request/command 118, a signal is sentto paper selector module 508 to initiate the paper sheet selectionprocess. Paper selector 508 then selects one or more sheets from tray702 and tray 704 for printing the document. The selected paper sheetsare then provided in an interleaved manner to print engine 108 forgenerating printed document 510. In one embodiment, paper selectormodule 508 ensures that printed document 510 comprises at least onefingerprinted sheet which can be used for authenticating the printeddocument. Different techniques, as previously described, may be used tointerleave fingerprinted paper sheets with non-fingerprinted papersheets while generating a printed document.

FIG. 8 is a simplified high-level flowchart 800 depicting afingerprinting process performed by a printer according to an embodimentof the present invention. The processing depicted in FIG. 8 may beperformed by software modules (code, instructions), hardware modules, orcombinations thereof. The processing may be performed by fingerprintingsystem 106. Flowchart 800 depicted in FIG. 8 is merely illustrative ofan embodiment of the present invention and is not intended to limit thescope of the present invention. Other variations, modifications, andalternatives are also within the scope of the present invention.

As depicted in FIG. 8, a condition is detected by the fingerprintingsystem that causes the fingerprinting system to start the fingerprintingprocess (step 802). For example, fingerprinting may be initiated whenthe fingerprinting system detects that the supply of fingerprinted papersheets has fallen below a preconfigured threshold. The threshold may beuser-configurable. A paper sheet is transported from a first paper trayto the fingerprinting system for fingerprinting (step 804). Thefingerprinting system scans the paper sheet received from the firstpaper tray and generates a fingerprint for the paper sheet (step 806).Information is then stored associating the fingerprinted paper sheetwith the generated fingerprint (step 808). The information may be storedin a memory associated with a second paper tray where the fingerprintedpaper sheet is to be stored. The fingerprinted paper sheet is thentransported to a second paper tray that is separate from the first trayand the fingerprinted paper sheet is made available for printing (step810). Steps 804, 806, 808, and 810 are applied to each paper sheetselected for fingerprinting from the first tray.

As described above, paper sheets are fingerprinted prior to them beingavailable for printing. The fingerprinting is performed offline from theprinting process and not as part of the printing process. Thefingerprinting operation is thus decoupled from the printing operation.Pre-fingerprinted sheets are then made available for the printingoperation. As a result, the fingerprinting operation does not act as abottleneck for the printing operation since a stack of previouslyfingerprinted sheets is available for printing. The printing operationmay thus be performed at high speeds as desired.

Although specific embodiments of the invention have been described,various modifications, alterations, alternative constructions, andequivalents are also encompassed within the scope of the invention. Thedescribed invention is not restricted to operation within certainspecific data processing environments, but is free to operate within aplurality of data processing environments. Additionally, although thepresent invention has been described using a particular series oftransactions and steps, it should be apparent to those skilled in theart that the scope of the present invention is not limited to thedescribed series of transactions and steps.

Further, while the present invention has been described using aparticular combination of hardware and software, it should be recognizedthat other combinations of hardware and software are also within thescope of the present invention. The present invention may be implementedusing hardware, software, or combinations thereof.

The specification and drawings are, accordingly, to be regarded in anillustrative rather than a restrictive sense. It will, however, beevident that additions, subtractions, deletions, and other modificationsand changes may be made thereunto without departing from the broaderspirit and scope of the invention as set forth in the claim.

1. A method performed by a printer, the method comprising: generating afingerprint for a paper sheet from a first tray of the printer; storinginformation in memory associating the fingerprint with the paper sheet;and transporting the paper sheet to the first tray after a fingerprintis generated for the paper sheet, wherein the paper sheet is madeavailable for printing.
 2. The method of claim 1 further comprising:receiving a request to print an electronic document; selecting at leastone fingerprinted paper sheet from the first tray for printing theelectronic document; and generating a printed document using the atleast one fingerprinted paper sheet from the first tray.
 3. The methodof claim 2 further comprising selecting a non-fingerprinted paper sheetfrom a second tray of the printer different from the first tray andwherein generating the printed document comprises using thenon-fingerprinted paper sheet for generating the printed document. 4.The method of claim 2 wherein the request to print specifies a page ofthe electronic document for which a fingerprinted paper sheet is to beused for printing the electronic document.
 5. The method of claim 2further comprising storing information for the at least onefingerprinted paper sheet associating the fingerprint generated for theat least one fingerprinted paper sheet with information related to theelectronic document.
 6. The method of claim 5 wherein the informationrelated to the electronic document comprises information related tocontents of the electronic document printed on the at least onefingerprinted paper sheet.
 7. The method of claim 1 further comprising:determining if the paper sheet received from the first tray comprises amark indicating that the paper sheet has been previously fingerprinted;and wherein generating a fingerprint for the paper sheet comprisinggenerating a fingerprint for the paper sheet only if it is determinedthat the paper sheet does not comprise the mark or the paper sheetcomprises a mark that is not decipherable by the printer.
 8. The methodof claim 1 wherein generating the fingerprint is performed upondetecting insertion of the first tray in the printer.
 9. The method ofclaim 1 wherein generating the fingerprint comprises marking the papersheet to indicate that the paper sheet has been fingerprinted.
 10. Themethod of claim 9 wherein marking the paper sheet comprises printing acode on the paper sheet wherein the code is at least one of a barcode, acode printed using infrared ink, and a code printed using an ink thatbecomes transparent upon exposure to light.
 11. The method of claim 9wherein marking the paper sheet comprises using a steganographictechnique to mark the paper sheet.
 12. The method of claim 1 whereingenerating the fingerprint comprises transporting the paper sheet fromthe first tray to a scanner.
 13. A method performed by a printer offingerprinting a paper sheet, the method comprising: selecting a set ofone or more paper sheets from a stack of paper sheets stored in a firsttray of the printer; generating a fingerprint for each paper sheet inthe selected set of paper sheets; storing in memory, for each papersheet in the set of paper sheets, information associating thefingerprint generated for the paper sheet with the paper sheet; andtransporting the set of paper sheets to a second tray of the printerseparate from the first tray.
 14. The method of claim 13 furthercomprising: receiving a request to print an electronic document; andgenerating a printed document in response to the print request, whereinthe printed document comprises a fingerprinted paper sheet from thesecond tray and a non-fingerprinted paper sheet from the first tray. 15.A printer comprising: a first tray for storing one or more paper sheets;a fingerprinting system configured to generate a fingerprint for a papersheet from the first; and a memory configured to store informationassociating the fingerprint with the paper sheet; wherein the first trayis configured to receive the paper sheet from the fingerprinting systemafter the fingerprinting system has generated a fingerprint for thepaper sheet, and the paper sheet is made available for printing upon thefirst tray receiving the paper sheet from the fingerprinting system. 16.The printer of claim 15 further comprising a print module configured to:receive a request to print an electronic document; select at least onefingerprinted paper sheet from the first tray for printing theelectronic document; and generate a printed document using the at leastone fingerprinted paper sheet from the first tray.
 17. The printer ofclaim 16 wherein the print module is configured to select anon-fingerprinted paper sheet from a second tray different from thefirst tray and generate the printed document using the non-fingerprintedpaper sheet.
 18. The printer of claim 16 wherein the request to printspecifies a page of the electronic document for which a fingerprintedpaper sheet is to be used for printing the electronic document.
 19. Theprinter of claim 16 wherein the memory is configured to storeinformation for the at least one fingerprinted paper sheet associatingthe fingerprint generated for the at least one fingerprinted paper sheetwith information related to the electronic document.
 20. The printer ofclaim 19 wherein the information related to the electronic documentcomprises information related to contents of the electronic documentprinted on the at least one fingerprinted paper sheet.
 21. The printerof claim 15 wherein the fingerprinting system is configured to:determine if the paper sheet received from the first tray comprises amark indicating that the paper sheet has been previously fingerprinted;and generate a fingerprint for the paper sheet only if it is determinedthat the paper sheet does not comprise the mark or the paper sheetcomprises a mark that is not decipherable by the printer.
 22. Theprinter of claim 15 wherein the fingerprinting system is configured togenerate the fingerprint upon detecting insertion of the first tray inthe printer.
 23. The printer of claim 15 wherein the fingerprintingsystem is configured to mark the paper sheet to indicate that the papersheet has been fingerprinted.
 24. The printer of claim 23 wherein thefingerprinting system is configured to print a code on the paper sheetwherein the code is at least one of a barcode, a code printed usinginfrared ink, or a code printed using an ink that becomes transparentupon exposure to light.
 25. The printer of claim 23 wherein thefingerprinting system is configured to use a steganographic technique tomark the paper sheet.
 26. The printer of claim 15 wherein thefingerprinting system comprises a scanner configured to receive thepaper sheet from the first tray.
 27. A system comprising: a first trayconfigured to store a stack of paper sheets; a fingerprinting systemconfigured to generate a fingerprint for each paper sheet in a set ofpaper sheets, the set of paper sheets selected from the stack of papersheets stored in the first tray; a memory configured to store, for eachpaper sheet in the set of paper sheets, information associating thefingerprint generated for the paper sheet with the paper sheet; and asecond tray configured to receive a paper sheet from the set of papersheets from the fingerprinting system after the fingerprinting systemhas generated a fingerprint for the paper sheet.
 28. The system of claim27 further comprising a print module configured to: receive a request toprint an electronic document; and generate a printed document inresponse to the print request, wherein the printed document comprises afingerprinted paper sheet from the second tray and a non-fingerprintedpaper sheet from the first tray.